ASTRO: ARP 78

Arp 78 is classified as a "spiral with small, high surface brightness
companion". The main galaxy is the SAb spiral NGC 772 and the small
high surface brightness companion is the NGC 770, an E3 elliptical. The
pair are about 100 million light years away. What about the other two
bright galaxies in the area? Wish I knew. I can find little on them
but a couple catalog entries that just show their location and
approximate brightness. The only one in the area I can find anything on
is [WGB2006] 015624+18430 g to the east (left) of NGC 772. Its red
shift distance is 112 million light years so is part of the same system
and obviously a dwarf as is NGC 770. No classification was given
however so it is little studied. The whole area is identified as the
galaxy group LGG 040. A group classification means they appear as a
group in our sky, not that they are necessarily a true cluster of
related galaxies. LGG stands for Lyon Group of Galaxies catalogue. The
notes say it is a group of 4. Now which other galaxy is in the group I
don't know. From the coordinates it may not include [WGB2006]
015624+18430 g but instead include the two galaxies west (right) of NGC
770 that I can't find much on.

Apparently the density of NGC 770 is rather high as it seems to have
really distorted the spiral structure of NGC 772 but only triggered star
formation in the core of the long major arm rather than throughout the
galaxy as is often the case in such near passages. It might be we need
more time as this appears to be a rather recent near miss. Though we
sure do see lots of "debris" from the event scattered about. Makes you
wonder what those beings (if any) living in the star systems pulled from
the galaxy think about all this.

Many very distant galaxy groups (clusters?) appear throughout the image.
None of which can I find in any catalog I have. Adding to the
confusion The Sky gives PGC numbers for positions where it shows no
galaxy no matter where you set the viewing parameters nor are these
known to the LEDA catalog which replaces the PGC one. Apparently they
were errors in the original catalog. The S0 spiral near the upper right
corner is LEDA 7421. It is shown by NED to have a red shift light
travel distance of about 215 million light years so is twice as distant
as ARP 78.

This image was taken with light snow on the ground but no ice yet on the
lake. Snow and ice really hurt my images costing me several magnitudes
and screwing up color balance of nebula and galaxies even when G2 stars
are white. I don't understand this nor am I good at correcting it. It
didn't help that clouds cut short the color run and I forgot that until
it is now too far west to get good data on. Thus the galaxy seems a
rather odd color. Fixing it really screwed up the stars so left it
where it was. I need to try again without the snow and ice crystals in
the air. This time of the year as the temperature drops a fog forms
over the lake cutting short my imaging many nights. So if not the ice
then the ice fog gets me. You know its winter when even before you turn
on cooling the camera reads -36C! Fortunately I have a backlog to
process taken before this problem developed, I just need to find the
time to work on them.

14" LX200R @ f/10, L=4x10' binned 2x2, RGB=1x10' binned 3x3,
STL-11000XM, Paramount ME

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

Very nice picture and good informations to go with it.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 78 is classified as a "spiral with small, high surface brightness
companion". The main galaxy is the SAb spiral NGC 772 and the small
high surface brightness companion is the NGC 770, an E3 elliptical. The
pair are about 100 million light years away. What about the other two
bright galaxies in the area? Wish I knew. I can find little on them
but a couple catalog entries that just show their location and
approximate brightness. The only one in the area I can find anything on
is [WGB2006] 015624+18430 g to the east (left) of NGC 772. Its red
shift distance is 112 million light years so is part of the same system
and obviously a dwarf as is NGC 770. No classification was given
however so it is little studied. The whole area is identified as the
galaxy group LGG 040. A group classification means they appear as a
group in our sky, not that they are necessarily a true cluster of
related galaxies. LGG stands for Lyon Group of Galaxies catalogue. The
notes say it is a group of 4. Now which other galaxy is in the group I
don't know. From the coordinates it may not include [WGB2006]
015624+18430 g but instead include the two galaxies west (right) of NGC
770 that I can't find much on.

Apparently the density of NGC 770 is rather high as it seems to have
really distorted the spiral structure of NGC 772 but only triggered star
formation in the core of the long major arm rather than throughout the
galaxy as is often the case in such near passages. It might be we need
more time as this appears to be a rather recent near miss. Though we
sure do see lots of "debris" from the event scattered about. Makes you
wonder what those beings (if any) living in the star systems pulled from
the galaxy think about all this.

Many very distant galaxy groups (clusters?) appear throughout the image.
None of which can I find in any catalog I have. Adding to the
confusion The Sky gives PGC numbers for positions where it shows no
galaxy no matter where you set the viewing parameters nor are these
known to the LEDA catalog which replaces the PGC one. Apparently they
were errors in the original catalog. The S0 spiral near the upper right
corner is LEDA 7421. It is shown by NED to have a red shift light
travel distance of about 215 million light years so is twice as distant
as ARP 78.

This image was taken with light snow on the ground but no ice yet on the
lake. Snow and ice really hurt my images costing me several magnitudes
and screwing up color balance of nebula and galaxies even when G2 stars
are white. I don't understand this nor am I good at correcting it. It
didn't help that clouds cut short the color run and I forgot that until
it is now too far west to get good data on. Thus the galaxy seems a
rather odd color. Fixing it really screwed up the stars so left it
where it was. I need to try again without the snow and ice crystals in
the air. This time of the year as the temperature drops a fog forms
over the lake cutting short my imaging many nights. So if not the ice
then the ice fog gets me. You know its winter when even before you turn
on cooling the camera reads -36C! Fortunately I have a backlog to
process taken before this problem developed, I just need to find the
time to work on them.

14" LX200R @ f/10, L=4x10' binned 2x2, RGB=1x10' binned 3x3,
STL-11000XM, Paramount ME

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".